1. Field of the Invention
Diaryl sulfones are useful as polymer additives and as intermediates for the preparation of polymers. The present invention is a process for their production by reacting an aryl sulfonic acid with an aryl reagent containing an active hydrogen atom.
2. Description of the Prior Art
A number of processes have been described in the literature for the manufacture of diaryl sulfones, including the following:
U.S. Pat. No. 3,125,604 to G. B. Robbins teaches reaction of an aryl sulfonic acid and a nonsulfonated hydrogen-aryl compound in the presence of a pentavalent phosphorus halide which acts as a condensing agent for the reaction.
U.S. Pat. No. 3,501,532 to J. T. Minor et al. teaches the reaction of an aromatic sulfonic acid with an aromatic compound having a replaceable hydrogen atom in the presence of a polyphosphoric acid having a phosphoric anhydride content of from about 75-85% which acts as a condensing agent.
U.S. Pat. No. 3,579,590 to D. S. Davis teaches production of diaryl sulfones by reacting aryl compounds having an active hydrogen, anhydrous sulfonating agent, and a non-metallic condensing agent (e.g., P.sub.2 O.sub.5, phosphorus pentachloride, phosphorus oxychloride, and boric anhydride).
U.S. Pat. No. 3,673,259 to J. Rosin et al. advocates the condensation reaction of an arylsulfonyl chloride with an arene by conducting the condensation reaction in the presence of relatively large amounts of a particular arylsulfonic acid which corresponds to such arylsulfonic chloride, substantially in the absence of any metal salts.
U.S. Pat. No. 3,729,517 to W. J. I. Bracke teaches formation of dialkaryl sulfones by first treating an alkaryl compound with concentrated sulfuric acid in a first step to convert it to a sulfonic acid with the second stage being initiated by a catalytic amount of P.sub.2 O.sub.5 to merely initiate the reaction with water thereafter being distilled off azeotropically.
U.S. Pat. No. 3,855,312 to P. J. Horner relates to a process for preparation of di-4-chlorophenyl sulphone in which a reaction mixture containing 4-chlorobenzenesulphonic acid and chlorobenzene is reacted at elevated temperature and superatmospheric pressure, water is removed as it is formed, and water and accompanying chlorobenzene are condensed and separated with the chlorobenzene being returned to the reaction mixture.
U.S. Pat. No. 4,558,161 to Y. Morita et al. covers reaction of chlorosulfonic acid with a mixture of an aromatic hydrocarbon and an aromatic sulfonic acid with hydrochloric acid gas evolved during the reaction being continuously removed.
Chemical Abstracts, Vol. 70, 57419t (1969), abstracting Japanese No. 68 24,662, describes reaction of an aromatic sulfonic acid with an aromatic hydrocarbon in the presence of a phosphorus oxide dehydrating agent, such as P.sub.2 O.sub.5.